This invention relates generally to gasification systems, and more particularly, to a system and methods for treating transient process gas.
At least some known gasification systems, such as those used in power plants, include a gasification system that is integrated with at least one power-producing turbine system, thereby forming an integrated gasification combined cycle (IGCC) power generation system. For example, known gasification systems convert a mixture of fuel, air or oxygen, steam, and/or CO2 into a synthetic gas, or “syngas”. The syngas is channeled to the combustor of a gas turbine engine, which powers a generator that supplies electrical power to a power grid. Exhaust from at least some known gas turbine engines is supplied to a heat recovery steam generator (HRSG) that generates steam for driving a steam turbine. Power generated by the steam turbine also drives an electrical generator that provides electrical power to the power grid.
At least some known gasification systems associated with IGCC systems initially produce a “raw” syngas fuel that includes carbon monoxide (CO), hydrogen (H2), hydrogen sulfide (H2S) and carbon dioxide (CO2). Hydrogen sulfide is commonly referred to as an acid gas. Acid gas is generally removed from the raw syngas fuel to produce a “clean” syngas fuel for combustion within the gas turbine engines. At least some known acid gas removal is performed with an acid gas removal subsystem that typically includes at least one main absorber to remove a majority of the H2S.
At least some known systems may be incapable of meeting current emissions requirements during all operating conditions. For example, high sulfur start-up fuels may produce a large quantity of emissions. Although most of such emissions generated may be captured during the acid gas removal process, at least some of such emissions may be released into the atmosphere during transient operating periods, such as system startups, shutdowns, and equipment trips.